The present invention relates to a projection type image display, in which light emitted from a light source side is radiated onto an image display element such as a liquid crystal panel and an optical image corresponding to a video signal is formed and projected on a larger scale.
A conventional technique related to the present invention is described, for example, in Japanese Patent No. 2800812 (Patent Document 1). In Patent Document 1, as a prism for color synthesis of light after modulated by a transmission type light valve, there is described a prism having two types of dichroic surfaces. The surfaces reflect red light (hereinafter referred to as “R light”) and blue light (“B light” hereinafter) and transmit green light (“G light” hereinafter).